Color-changing gold tattoo can monitor your health

Researchers have found a way to use gold nanoparticles to help diagnose medical problems by embedding them in an invisible tattoo.

Who doesn’t want a little gold on their body? Some bling around the neck can be a sign of wealth, but according to a new study, wearing gold nanoparticles can also provide information about your health.

Researchers in Germany have found a way to use gold nanoparticles to help diagnose medical problems, using an  “invisible tattoo.”

The idea of implantable sensors to track human health has been growing for some time. Already, tiny wearable health monitors are gaining interest for monitoring things like sweat and mood, blood pressure, glucose, and heart rate.

But researchers are seeking the next level — sensors that would enable doctors to track disease development or drug concentrations in the body in real-time. Many implantable sensors aren’t sophisticated enough to stay in the body for long periods. The body rejects them, or they stop working.

A team at Johannes Gutenberg University Mainz in Germany may have a solution. They have developed an implantable sensor that can remain in the body for several months. The secret ingredient is gold nanoparticles.

Using color-stable gold nanoparticles, modified with unique molecule receptors, they created a sensor that can be embedded under the skin. Once there, it will change color to indicate changes in drug concentrations.

“Our sensor is like an invisible tattoo, not much bigger than a penny and thinner than one millimeter,” Carsten Soennichsen, head of the Nanobiotechnology Group at JGU, said in a statement.

The infrared color variations in gold nanoparticles are invisible to the naked eye, so researchers must use a special instrument to test their color through the skin.

The team embedded the sensors into a porous hydrogel that has a tissue-like consistency. The gel protects the gold nanoparticles from attacks by the immune system. Once the sensor is inserted under the skin, tiny blood vessels can expand and grow into the porous gel, connecting the body to the sensor, reports European Scientist.

They tested the sensors on hairless rats and looked for color changes after administering various doses of an antibiotic. The drugs passed through the bloodstream to enter the sensor and bind to receptors on the gold nanoparticles. This causes a color shift that was proportional to drug concentration, reports Mining.

“We are used to colored objects bleaching over time. Gold nanoparticles, however, do not bleach but keep their color permanently. As they can be easily coated with various different receptors, they are an ideal platform for implantable sensors,” stated researcher Katharina Kaefer.

This new work, published in Nano Letters, could be advantageous to personalized medicine by increasing the lifespans of implantable sensors that track drugs or biomarkers in the body.

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